I've always seen pedangs with this sort of hilt being attributed to Sumatra, and Adni manages to find a lot of these on his sourcing trips to Sumatra too. However, I would not be surprised that the Makara is a motif that has spread throughout Indonesia and Malaysia, given the pervasive Indian influences in the past.
I attach pictures of a Badik Makara carved by Mr Nik Rashidee. The posture of the Makara is reminiscent of the abstract Makara that you see on the pedangs.
Apparently, the collar of some sewar sheaths are also representations of the Makara with the trunk curled over the head.
The Makara is the vehicle of the goddess Ganga, and in India, it has been described as a sea monster with parts of many different animals, including the body of a crocodile. However, the Makara in southeast asia invariably always have features of an elephant. Some other parts commonly found on the southeast asian makara include tail of a fish, horns of a goat, tusks of a wild boar. Some versions also include the crown of a king.
Talking about the kakatua, some sewar and pedangs have abstract representations of the kakatua too. Look at this tumbuk lada, for instance. It looks like leaves and 'jantung pisang' (literally, heart of the banana - its the phallic-shaped part of the banana bunch) put together, but then, there's a kakatua form hidden in it.
http://www.kampungnet.com.sg/modules...view_photo.php
And then, there are the Moro kris and barong with the kakatua form on the pommel, and perhaps on the sheath too.
http://www.kampungnet.com.sg/modules...view_photo.php